The dichotomy of placenta-derived cells in cancer growth.

Placenta-derived mesenchymal stromal cells (MSC) have often been considered to linger behind their equivalents from other tissues, such as MSC from bone marrow, in many aspects including their therapeutic potential in regenerative medicine. Nowadays however, it is clear that certain aspects make placental MSC attractive as a cellular therapy, such as their lack of ethical concerns and ease of isolation from human term placenta, a material long regarded as biological waste. Moreover, placental MSC virtually lack expression of human leukocyte antigens and co-stimulatory molecules, making them very attractive for transplantation in allogeneic settings. In the context of cancer, cell therapy remains an area of intense investigation whereby MSC have been shown to play opposing roles, and placental MSC are no exception. In this review, we will discuss dichotomy of placental MSC that underscores the challenges in understanding their therapeutic potential in oncology.